Dynamic Recrystallization Mechanisms of As‐Extruded GH4151 Alloy during Hot Deformation

Abstract

Different degrees of deformation, as an important forming method in the machining process, which has an important influence on the dynamic recrystallization (DRX) behavior. In this study, we investigated the effect of different deformation strains on the microstructure evolution and deformation mechanism of as‐extruded GH4151 nickel‐based superalloy using isothermal hot compression. As a result, the average grain size decreased with the increase of deformation, and the proportion of Σ3 boundaries tended to decrease and then increase with the increase of DRX grain volume fraction, indicating that the presence of twins had a facilitating effect on the nucleation of DRX. In addition, discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) coexisted during hot deformation, and DDRX was the main nucleation mechanism. CDRX was easy to occur at middle strain of 50%, and its nucleation mode was subgrain rotation nucleation. And there were two types of nucleation for DDRX: grain boundary bulging nucleation and twin‐assisted nucleation.